New York (USA Today)-- More than a day after an explosion leveled two collapsed buildings in East Harlem, the search continued for as many as five people still missing.

An eighth body was removed Thursday morning.

It was still too dangerous for investigators from the National Transportation Safety Board (NTSB) to examine the site, board member Robert Sumwalt said Thursday afternoon.

Sumwalt described the aftermath of the explosion in one word: "Devastating."

"You've got basically two five-story buildings that have been reduced to essentially a three-story pile of bricks and twisted metal," he said. "I've seen an occasional flare-up of fire and the smell of smoke is ominipresent. All of this underscores that this is an active search-and-recovery operation. First responders are carefully removing debris."

The NTSB is assuming that the blast was caused by a natural gas leak but hasn't ruled out the possibility that an apartment's stove could be to blame, Sumwalt said.

He noted that the gas main and distribution pipe were intact, which is different from other explosions where pipes have been blown several feet from a building.

"We will be constructing a timeline," Sumwalt said. "We aren't sure how long the leak was there."

The NTSB will try to determine whether there is a relationship between the explosion and a nearby water main break.

Sumwalt said his agency is focused on preventing such an incident from happening again.

"Many people's lives have been shattered, and we don't take that lightly," he said.

The NTSB's responsibilities include pipelines.

As many as 60 people were injured when the blast, apparently triggered by a natural gas leak, leveled the five-story buildings, which included Spanish Christian Church, 15 apartments and a piano repair store.

"I can only imagine knowing that at any moment you might find a body, how difficult that is," Mayor Bill de Blasio told firefighters on his second visit in two days to the blast site on Park Avenue at 116th Street.. "I admire the work you guys do. I really do. It's not easy. Thank God you do."

Thomas Perez, pastor of Spanish Christian church, said four members of his congregation are among the dead. He added that one young man who had been married for only four months is still missing.

Perez, standing about a block from the blast site, described the terrible anxiety enveloping his church members as rescuers continued to search the ruins of the building where they once worshiped.

"The families are brokenhearted," he said. "I'm the pastor and they were my children, and some of them are missing in such a horrible way. But, what can we do? It's life."

Perez, wearing a thick wool coast and face mask, said the church was "praying for the Lord to keep us together."

"The building is no longer there but we are still here, and we're going to keep on going," he said.

Work crews, using thermal imaging cameras to locate bodies or pockets of smoldering fire, found the latest victim shortly after 7 a.m. ET Thursday.

Sandra Aponte, 30, a medical office service representative, is concerned about the air quality in the area of the blast site. She exits the train station every day a block from the rubble and fears the fallout from the explosion will complicate her medical condition.

"I'm asthmatic, so this is definitely worrying me," Aponte said Thursday as she covered her nose and mouth with a scarf. "It smells really bad. Masks are definitely necessary around here."

On Wednesday, she was greeted with a smell of gas on her way to work but didn't imagine it would lead to tragedy. She felt the explosion at her office two blocks away from the leveled buildings.

"I felt the floor just shake a little bit, but it was mostly the boom -- the inner feeling of complete shock," Aponte said.

Dozens of police officers, reporters, residents and garbage men wore small masks against the stench that hung in the air more than a day after the explosion.

"This is a difficult job, a challenging job," New York Fire Department spokesman Jim Long said. He said it was "a very terrible and traumatic scene."

Hunter College identified one victim as Griselde Camacho, a 45-year-old security officer who worked for the university since 2008. Also killed was Carmen Tanco, 67, a dental hygienist. Her cousin, News 12 cameraman Angel Vargas, said the family started a frantic search when she didn't show up for work Wednesday.

Officials in Mexico said two of the victims came from the central Mexican state of Puebla. The state's government identified them as Rosaura Barrios Vazquez, 43, and Rosaura Hernandez Barrios, 22. The government did not say whether the women were related.

New York police had put Hernandez Barrios' age at 21.The bodies of three unidentified men also were pulled from the rubble, authorities said.

At least three of the injured were children. One, a 15-year-old boy, was reported in critical condition with burns, broken bones and internal injuries. Most of the other victims' injuries were minor and included cuts and scrapes.

The cause of the blast has centered on reports of leaking natural gas. De Blasio said the explosion erupted only minutes before a crew from the Con Edison power company arrived to check for a reported leak..

Elhadj Sylla, whose wife owns a store nearby, said he was about a block away around 8:45 a.m. when he noticed a faint smell of gas.

Ruben Borrero, a tenant in one of the destroyed buildings, said residents had complained to the landlord about smelling gas as recently as Tuesday.

A few weeks ago, Borrero said, city fire officials were called about the odor, which he said was so bad that a tenant on the top floor broke open the door to the roof for ventilation.

"It was unbearable," said Borrero, who lived in a second-floor apartment with his mother and sister, who were away at the time of the explosion. "You walk in the front door and you want to turn around and walk directly out."

Edward Foppiano, a Con Ed senior vice president, said there was only one gas odor complaint on record with the utility from either address, and it was last May at the building next door to Borrero's. It was a small leak in piping and was fixed, he said.

The block was last checked on Feb. 28 as part of a regular leak survey and no problems were detected, he said.

David Moore, 52, lives in Brooklyn but happened to be in East Harlem on Thursday and stopped by the scene of the explosion.

He stood near a barricade peering into the remains of the explosion for several minutes as other onlookers did the same.

Moore said the stench of burning materials causing people to cover their noses and mouths reminded him of another city tragedy.

"It's very similar to the aftermath of 9/11 as far as the smell of fire and smoke is concerned," Moore, an accountant, said. "(With) 9/11, I got down there about two weeks after the event occurred but there was still a smell in the air. It was a bit worse than this one."

"It was just a terrible accident and a tragedy," he said. "It can happen in any part of the country, any borough."